The traditional method of making hay is to cut the standing crop with a mower and allow it to air dry while lying in the swath in the field. Once the hay has dried to approximately 20% moisture or below, it is raked into windrows and baled and/or stacked either in open stacks or under shelters. Sometimes, the crop is crushed after cutting in order to hasten drying, and sometimes the crop is raked into windrows, before it is air dry, so that handling of the dry crop is reduced.
The greatest mechanical losses occur when the crop is handled in the dry state because dry leaves shatter and are lost. Besides mechanical loss, dry matter losses occur during the drying process because of metabolic activity of the plant and some activity of bacteria and fungi. When the moisture content of the hay drops to 20% or less, metabolic activity of the plant tissues and of bacteria and fungi drops to a very low level.
The chief disadvantage of this method is that the crop must lie in the field during the drying process, and there is considerable risk that it will be damaged or destroyed by rain. At present, only costly artificial drying equipment permits storage of hay that is not fully dried in the field. Hay that is stored with moisture levels above 20% is likely to deteriorate badly due to fungi and bacterial action. When moisture content exceeds 30%, such deterioration is certain. Sometimes the heat generated by metabolic activity in moist hay triggers processes leading to spontaneous combustion. This endangers not only the hay but also the structure in which it is stored.
Crop residue, such as corn stalks, are picked up by flail type implements and stacked. Sometimes, the residues are blown into wagons directly from the grain harvesting machine and then stacked. Drying conditions after fall grain harvest are generally poor. Frequently, the moisture content of the residual material exceeds 20% when it is stacked, and it often becomes moldly or musty. In this condition, its acceptability to animals and its nutritional value are considerably reduced.
Several products are now in use as hay preservatives. These are organic acids, such as propionic acid and its derivatives. They serve primarily as fungicides and do not enhance the quality of the original product.
Thus, it can be appreciated from the foregoing that devices and methods have been needed to allow better and more efficient ways of making hay and storing the same. Included is the necessity to better preserve the hay and thus facilitate making and storing the same. The same is likewise true of at least some other compressible fibrous materials.